Isolation and structure determination of terminalin a toxic condensed tannin from Terminalia oblongata

Abstract

Terminalia oblongata (yellow wood) is a small deciduous tree growing over an area of central Queensland that supports a large proportion of this state's cattle population. Cattle and sheep that consume yellow wood leaves are poisoned and die. Severe losses of these animals can occur, and this problem is considered the main cause of economic loss to the cattle industry in the area apart from drought. A new toxic condensed tannin, terminalin was isolated from Terminalia oblongata. Its structure was deduced following NMR, IR, UV, MS analyses and in the knowledge that these data show good correlations to those obtained from the related punicalagin molecule which is present in the plant. Terminalin has a high toxicity (20 mg/kg) to white Quackenbush male mice and produces a vascular renal necrosis with slight liver necrosis, unlike punicalagin, which produces liver lesions but not kidney lesions. Similar results were obtained with sheep. A most interesting aspect is that there are two different specific toxins in the plant.

Antioxidant and hepatoprotective effects of punicalagin and punicalin on acetaminophen‐induced liver damage in rats

“…Even if punicalagin and punicalin exert great superoxide scavenging activity in vitro, the rat liver SOD activity after treatment with punicalagin or punicalin was not prominently reduced (Table 2). According to the study by Oelrichs et al (1994), punicalagin can cause liver injuries, and our related results in these studies coincide with them. Although these condensed tannins present great antioxidative activity in vitro and prevent acetaminopheninduced liver injury under a certain range of doses, they may cause liver injuries when used at a larger dose.…”

The effects of aqueous extracts prepared from the leaves of Pistacia lentiscus in experimental liver disease

“…This discrepancy obviously warrants further investigation. We know the leaves of Pistacia lentiscus contain condensed tannins that are proven hepatotoxins (Oelrichs et al, 1994;Decandia et al, 2000). Therefore, we can only speculate that long-term Fig.…”

Fagaceae Dumort

“…Condensed tannins, or proanthocyanidins, as they are referred to, for the most part pass unchanged through the digestive tract and, with few exceptions, appear to contribute little to systemic disease problems (Haslam 1989;Oelrichs et al 1994). These tannins are resistant to hydrolysis and tend to polymerize to yield amorphous compounds known as phlobaphens.…”

“…Thus it is not surprising that tannins of some type are suspected as the toxicants in other plant families. The effects of T. oblongata are an exception in that toxicity is apparently due to a combination of hydrolyzable and condensed tannins, the former causing liver disease and the latter causing kidney disease (Oelrichs et al 1994). A hydrolyzable tannin, punicalagin (an ellagitannin), has been identifi ed as one of the toxic principles in Terminalia oblongata, in the Combretaceae; it causes acute liver disease in cattle and sheep in Australia (Filippich et al 1991).…”